This is invention relates to novel carbosilanes, polycarbosilanes synthesized therefrom, and the processes for producing the same.
Oligocarbosilanes are conventionally prepared by Grignard method or Wurtz method. For example, as reported by K. Nate, M. Ishikawa, H. Ni, H. Watanabe, and Y. Saheki in Organometallics, 6, 1673 (1987), an oligocarbosilane can be prepared by the following reaction. 
However, the above method is defective in that a compound having a desired molecular weight can seldom be prepared due to the difficulty in controlling the polymerization degree. The present inventor has studied intensively to improve on the defects of the prior art and finally found that using carbosilanes having specific organometallic groups at their terminals as a starting material can overcome the above problems. This finding has led to the present invention. Further, carbosilanes and polycarbosilanes of the present invention having the organometallic groups of the invention at their terminals are useful organic materials per se and are expected as a new material which is produced by using them as a macromonomer.
The method of the present invention makes it possible to produce polycarbosilanes with polymerization degree controlled by;
(1) using carbosilanes of the present invention having specific organometallic groups containing, e.g., a stannic atom at their terminals, as a starting material, and
(2) using organic typical metal compounds such as butyl lithium as an initiator.
By using both the compounds in combination, organometallic groups at the terminals are kept stable after completion of a polymerization reaction. Accordingly, addition of an organic typical metal compound as an initiator can restart the reaction to increase polymerization degree of polycarbosilanes. Polymerization degree of the polycarbosilanes can also be varied by changing the reaction time. The polymerization degree is controllable by these methods.